This article examines the collegial dynamics within investment tribunals. I construct a qualitative typology of adjudicator-level interactions based on original interviews with arbitrators from over 90% of finalized investment arbitrations. I proceed in several steps. First, I present an empirical and theoretical background on investment arbitration governance. Second, I give an overview of my data collection and method. I then present eight ideal types of arbitrators, which vary by their tilt towards states and affinity for each other. I then consider 128 distinct tribunal combinations, for which I explore the implications for states. I conclude that collegial dynamics contribute to making awards more investor-friendly or fact specific. The article contributes to the judicial politics and judicialization literatures by providing a case study of collegial dynamics among a class of adjudicators that lack tenure.

The article is part of a special issue on empirical research on investment treaties. Cedric Dupont and Thomas Schultz have a great introductory article, where they kindly summarize a major takeaway of my study:

The crucial and usually forgotten question about arbitrators, Tucker essentially
explains, is how likely they are to influence the other two arbitrators on the tribunal,
and not only in which direction they are likely to pull. Their likely persuasive effectiveness depends, among other things, on how willing they are to try, for reasons of personality but also other interests of their own, and how persuasive they can be if they do try.